1. Technical Field
The present invention relates to a vibrator element, a manufacturing method of the vibrator element, and a sensor unit and an electronic apparatus using the vibrator element.
2. Related Art
There is an angular velocity sensor (a vibration gyro sensor) or the like which is used for, for example, vehicle body control of a vehicle, own-vehicle position detection of a car navigation system, vibration control correction (so-called camera shake correction) of a digital camera or a video camera, and the like, and detects a physical quantity such as angular velocity, acceleration, or the like, as a sensor element (for example, JP-A-2008-14887).
An angular velocity sensor disclosed in JP-A-2008-14887 has a tuning fork which includes two arms and a base portion which connects first ends of the two arms to each other. In addition, in the angular velocity sensor disclosed in JP-A-2008-14887, the tuning fork is made of a non-piezoelectric body material, and an excitation portion and a detection portion in which a piezoelectric thin film is interposed between a pair of electrodes are provided for each arm.
In this angular velocity sensor, a voltage is applied between a pair of electrodes of an excitation portion, and thereby the arm performs flexural vibration (excitation). In addition, when the angular velocity around an axial line in an extension direction is applied to the arm in this excitation state, the arm of the detection portion is bent by the Coriolis force in a direction perpendicular to the above-described excitation direction, and charge generated according to a bending amount thereof is detected from the electrodes of the detection portion. The angular velocity can be detected based on the detected charge.
The above-described tuning fork having two arms is generally formed by etching a substrate. At this time, it is difficult to form the size of the tuning fork as designed due to etching anisotropy of the substrate, a variation in processing process, or the like. For this reason, the tuning fork is formed in an unintended shape, and thus there are cases where the arm of the detection portion is bent in a direction different from the flexural vibration direction even in a state in which the angular velocity is not applied thereto. If charge generated from a pair of electrodes of the detection portion due to bending of the arm is detected, detection accuracy is lowered.
Therefore, in the angular velocity sensor disclosed in JP-A-2008-14887, a pair of electrodes of the detection portion is partially removed, and thereby an amount of charge output from the detection portion in a state in which the angular velocity is not applied to the arm is adjusted.
However, in the method in which an amount of charge is adjusted by partially removing a pair of electrodes of the detection portion, in a case where an adjustment amount is large, a variation of a charge amount relative to a removal amount is required to be increased, and thus an accurate adjustment of a charge amount becomes difficult. In addition, if a variation of a charge amount relative to a removal amount is made to be small, an adjustment range is narrowed, and thus there is a problem in that the adjustment cannot be performed.